Window covering systems exist primarily to shield interior spaces from direct sunlight and to prevent others from viewing inside through the window. Conventional systems such as venetian blinds, drapes and shades may block direct sunlight effectively but do not permit diffuse light to enter for illumination purposes when they are closed. It is known that occupants tend to set conventional venetian blinds in a closed position and seldom adjust them.
Many examples of prior art window covering systems exist which attempt to block direct sunlight while allowing natural illumination. It is known to use a slat which is semi-transparent as a result of numerous pores being punched into the slat, known in the art as a "punched slat". In U.S. Pat. No. 5,423,367 issued to Kataoka et al. on Jun. 13, 1995, a partially punched slat is disclosed. In this patent, the slats are angle shaped and formed of a first punched section and a second non-light transmitting section wherein the two sections are joined at an angle. Thus, if the slats are rotated in one direction, the blind will appear semi-transparent and if they are rotated in another direction, the blind will appear closed. This system still requires user adjustment to provide interior illumination and cannot provide good illumination without compromising privacy and allowing direct sunlight to enter the room.
A similar approach is taken in U.S. Pat. No. 4,799,526 issued to Reeves. In this patent, the slat is partially or completely made of a transparent plastic such as a polycarbonate. This slat may be adjusted such that the blind is transparent or completely blocking if the slat also comprises an opaque portion. Again, these slats cannot provide illumination without compomising privacy or allowing direct sunlight to enter.
Therefore, there is a need in the art for a window covering system which permits diffuse light to enter and illuminate a room while blocking direct sunlight from entering the room and maintaining a privacy screen when desired.